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  2. Nebula - Wikipedia

    en.wikipedia.org/wiki/Nebula

    The Westbrook Nebula, a protoplanetary nebula. A protoplanetary nebula or preplanetary nebula [ 27 ] (PPN, plural PPNe) is an astronomical object which is at the short-lived episode during a star 's rapid evolution between the late asymptotic giant branch (LAGB) [a] phase and the subsequent planetary nebula (PN) phase.

  3. Veil Nebula - Wikipedia

    en.wikipedia.org/wiki/Veil_Nebula

    The Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus. [4]It constitutes the visible portions of the Cygnus Loop, [5] a supernova remnant, many portions of which have acquired their own individual names and catalogue identifiers.

  4. Astronomy - Wikipedia

    en.wikipedia.org/wiki/Astronomy

    Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets.

  5. Dark nebula - Wikipedia

    en.wikipedia.org/wiki/Dark_nebula

    A dark nebula or absorption nebula is a type of interstellar cloud, particularly molecular clouds, that is so dense that it obscures the visible wavelengths of light from objects behind it, such as background stars and emission or reflection nebulae.

  6. Planetary nebula - Wikipedia

    en.wikipedia.org/wiki/Planetary_nebula

    NGC 6326, a planetary nebula with glowing wisps of outpouring gas that are lit up by a binary [3] central star. A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. [4] The term "planetary nebula" is a misnomer because they are unrelated to ...

  7. Emission nebula - Wikipedia

    en.wikipedia.org/wiki/Emission_nebula

    The nebula's color depends on its chemical composition and degree of ionization. Due to the prevalence of hydrogen in interstellar gas, and its relatively low energy of ionization, many emission nebulae appear red due to strong emissions of the Balmer series. If more energy is available, other elements will be ionized, and green and blue ...

  8. Cosmochemistry - Wikipedia

    en.wikipedia.org/wiki/Cosmochemistry

    Meteorites are often studied as part of cosmochemistry. Cosmochemistry (from Ancient Greek κόσμος (kósmos) 'universe' and χημεία (khēmeía) 'chemistry') or chemical cosmology is the study of the chemical composition of matter in the universe and the processes that led to those compositions. [1]

  9. Nebular hypothesis - Wikipedia

    en.wikipedia.org/wiki/Nebular_hypothesis

    A protoplanetary disk forming in the Orion Nebula. The main problem in the physics of accretion disks is the generation of turbulence and the mechanism responsible for the high effective viscosity. [2] The turbulent viscosity is thought to be responsible for the transport of the mass to the central protostar and momentum to the periphery of the ...